get_tags( string|array $args = '' )

function get_tags( $args = '' ) {
	$tags = get_terms( 'post_tag', $args );

	if ( empty( $tags ) ) {
		$return = array();
		return $return;
	}

	/**
	 * Filters the array of term objects returned for the 'post_tag' taxonomy.
	 *
	 * @since WP-2.3.0
	 *
	 * @param array $tags Array of 'post_tag' term objects.
	 * @param array $args An array of arguments. @see get_terms()
	 */
	$tags = apply_filters( 'get_tags', $tags, $args );
	return $tags;
}